Graduating late + repeating grades in HS

I come from a country which follows the British O’levels and A’levels system. After my 11th grade (AS level), I went on an exchange year to USA and completed 12th grade there. Unfortunately, my high school there did not let me graduate so I am having to repeat both my AS and A2 again (11th and 12th grade) in my country so that I can also apply to colleges which require a high school diploma. The reason I am having to take 11th grade again is that under the Cambridge system, if you don’t sit for your A2 within a year of your AS, you’ll need to take them both again. This means that I will be graduating 2 years later than I would have under normal circumstances. I am
also taking different subjects than I did in my previous AS sitting because I wanted to expand a little more. I will still be 18 when I graduate as I was always young for my grade. I wanted to know if this may hurt my chances of getting into colleges in the U.S.? I plan to apply to a few Ivies and mostly top tier liberal arts colleges.

So what happend in 12 grade? You couldn’t graduate because of what reasons? (I assume you couldn’t possibly meet grad reqs in the yr, but how many APs did you do? That kind of thing) Why did you got to the USA for 12 grade? An exchange year with so little planning seems on the nose. You want a great explanation for your timeline. Basically you threw away a year. Were your AS levels top scores? You are basically spending 3 yrs in school after finishing 11th grade. You just need to make that sound reasonable. As always, cast a wide net, make sure to have match schools, if you are international requiring aid, have a back up plan at home.

^Many international students go on exchange for a year to discover US culture. They do not get credit for it and rarely get to graduate since they’re on exchange visas for a year. Those are the rules. American universities know that very well and actually appreciate the initiative it takes to move away and live away from home as a 16 or 17 year old. Not many students have the open-mindedness, maturity, psychological stability, and strong will required to do that.

To answer OP: it won’t hurt your prospects at all. They consider 4 AS level (up to 6) and 3 A levels (up to 4) taken over two years.
However, you’d need to diversify your list. Get a Fiske Guide or Princeton Review’s Best Colleges and find colleges with admission rates above 30% and above 40-45% for matches and safeties.